The invention relates to a process and to an apparatus for production of carbon black particles.
A known process for producing carbon black or industrial black is called the furnace process, in which a hot gas is first generated in a combustion chamber with controlled supply of air, and then a carbon base material, usually aromatic carbo- or petrochemical oils, is burnt therein at high temperatures, in order thus to generate free carbon, i.e. carbon black. This reaction is stopped abruptly by means of addition of water in the last step of the furnace process, the quenching, at the point when the carbon black particles formed have the desired size and properties.
The carbon black particles produced in this way have a size and structure in the nanometer range and, because of their low density, form a high level of dust and are transportable only with difficulty, and for that reason the quenching is followed directly by a compaction plant in which the carbon black particles are pelletized directly. This exploits the character of the gas/air stream used at the start, since this gas/air stream gives rise to a particle stream of carbon black particles which can be blown directly into the pelletizing system without needing to transport the carbon black particles. In the form of the pellets generated in the pelletizing system, the carbon black produced can then be transported without any problem.
By virtue of recent developments in carbon black production by pyrolysis from used tires, described, for example, in WO 2011/035812 A1, it is possible to obtain relatively pure carbon black in a recycling process as well. This recycled carbon black is less expensive than the standard carbon black produced in the furnace process described above. Therefore, it is desirable to add recycled carbon black to standard carbon black in order thus to be able to provide less expensive starting materials, for example for the tire industry.
Because of the process regime in the pyrolysis, recycled carbon black has different particle sizes. It is therefore ground in order to obtain a defined maximum particle size. Like standard carbon black, the ground recycled carbon black has a very low density and hence a very high volume, and so it has poor storability, conveyability and transportability. For this reason, recycled carbon black can also be pelletized in order that it has better storability, conveyability and transportability.
Simple mixing of different carbon black pellets prior to transport leads to undesirable bursting-open of the pellets as a result of shear forces that act during the mixing. Therefore, the carbon black species are converted back to their original undesirable form with low density and high volume, which is in turn unfavorable for storage, conveying or transport.
It is therefore an object of the invention to propose a process and an apparatus which enable mixing of different carbon black species without the abovementioned disadvantages.
This object is achieved by a process for producing hybrid carbon black particles as claimed in claim 1.
An apparatus for production of hybrid carbon black particles and a hybrid carbon black particle produced by the process are provided by the further independent claims.
Advantageous configurations of the invention are the subject of the dependent claims.